Reaction system for production of diesel fuel from vegetable and animals oils

ABSTRACT

A process for producing a fuel composition from vegetable and/or animal oil comprises feeding the oil to a tubular reaction unit containing a catalyst comprising an acidic component and a metal component, feeding effluent from the tubular reaction unit to a vapor-liquid separator, and feeding a vapor phase separated from the effluent from the tubular reaction unit to an adiabatic reaction unit comprising the same catalyst as in the tubular reaction unit comprising an acidic component and a metal component. The produced fuel composition has acceptable lubricity and comprises a mixture of C 12  to C 18  or C 14  to C 18  paraffins having a ratio of iso to normal paraffins of 2 to 8 and less than 5 ppm sulfur.

BACKGROUND

1. Field of Art

Provided is a process and reaction system for the production of liquidfuels, particularly diesel, jet and naphtha fuels, from vegetable and/oranimal oils.

2. Description of the Related Art

Most combustible liquid fuels used for on road, off road, stationaryengines, and combustion turbines and boilers in the world today arederived from crude oil. However, there are several limitations to usingcrude oil as a fuel source. For example, crude oil is in limited supply,includes a high content of aromatics, and contains sulfur andnitrogen-containing compounds that can adversely affect the environment.There is a great desire and need in the industry to provide combustibleliquid fuels that are more environmentally friendly, display good engineperformance, and which are available from alternative sources that areabundantly renewable.

Vegetable and animal oils are an abundant and renewable source. The useof vegetable oil in diesel engines requires significant enginemodification, including changing of piping and injector constructionmaterials, otherwise engine running times are decreased, maintenancecosts are increased due to higher wear, and the danger of engine failureis increased. The current conversion of vegetable and animal oils tocombustible liquid fuels typically involves transesterification of theoils, which are triglycerides of C₁₄ to C₂₂ straight-chain carboxylicacids, with a lower alcohol such as methanol or ethanol, to form amixture of methyl or ethyl esters called “biodiesel”. This process isrelatively complex, typical of the chemical industry rather than thepetrochemical industry. Furthermore, the composition of biodiesel, whichis completely different from that of diesel produced from crude oil, mayhave adverse effects on engine performance. Biodiesel exhibits poor lowtemperature performance characteristics and increased nitrogen oxide(NO_(x)) emissions compared to conventional fuels derived from crudeoil.

In the search for alternative and renewable sources, there is increasinginterest in producing liquid fuels from biological raw materials for useas fuel by themselves or in mixture with the petroleum-derived fuels inuse today. The patent literature describes methods for producinghydrocarbon mixtures from biological sources, including vegetable oils.

United Kingdom Patent Specification 1 524 781 discloses convertingester-containing vegetable oils into one or more hydrocarbons bypyrolysis at 300 to 700° C. in the presence of a catalyst whichcomprises silica-alumina in admixture with an oxide of a transitionmetal of Groups IIA, IIIA, IVA, VA, VIA, VIIA or VIII of the periodictable, preferably in a fluidized bed, moving bed or fixed bed tubularreactor at atmospheric pressure.

U.S. Pat. No. 5,705,722 discloses a process for producing additives fordiesel fuels having high cetane numbers and serving as fuel ignitionimprovers. In the process, biomass feedstock selected from (a) tall oilcontaining less than 0.5 wt % ash, less than 25 wt % unsaponifiables, upto 50 wt % diterpenic acids and 30 to 60 wt % unsaturated fatty acids,(b) wood oils from the pulping of hardwood species, (c) animal fats and(d) blends of said tall oil with plant or vegetable oil containingsubstantial amounts of unsaturated fatty acids or animal fats, issubjected to hydroprocessing by contacting the feedstock with gaseoushydrogen under hydroprocessing conditions in the presence of ahydroprocessing catalyst to obtain a product mixture. This productmixture is then separated and fractionated to obtain a hydrocarbonproduct boiling in the diesel fuel boiling range, this product being thehigh cetane number additive.

U.S. Patent Publication No. 2004/0055209 discloses a fuel compositionfor diesel engines comprising 0.1-99% by weight of a component or amixture of components produced from biological raw material originatingfrom plants and/or animals and/or fish and 0-20% of componentscontaining oxygen. Both components are mixed with diesel componentsbased on crude oil and/or fractions from Fischer-Tropsch process.

U.S. Patent Publication No. 2004/0230085 discloses a process forproducing a hydrocarbon component of biological origin comprising atleast two steps, the first one of which is a hydrodeoxygenation step andthe second one is an isomerization step operated using thecounter-current flow principle. A biological raw material containingfatty acids and/or fatty acid esters serves as the feed stock.

Fuel properties important for potential diesel applications include: (i)lubricity; (ii) cetane number; (iii) density; (iv) viscosity; (v) lowerheating value; (vi) sulfur; (vii) flash point; (viii) cloud point; (ix)Distillation Curve; (x) carbon residue; (xi) ash; and (xii) IodineValue. Lubricity affects the wear of pumps and injection systems.Lubricity can be defined as the property of a lubricant that causes adifference in friction under conditions of boundary lubrication when allknown factors except the lubricant itself are the same; thus, the lowerthe friction, the higher the lubricity. Cetane number rates the ignitionquality of diesel fuels. Density, normally expressed as specificgravity, is defined as the ratio of the mass of a volume of the fuel tothe mass of the same volume of water. Viscosity measures the fluidresistance to flow. Lower heating value is a measure of available energyin the fuel. Flash point is the lowest temperature at which acombustible mixture can be formed above the liquid fuel. Cloud pointmeasures the first appearance of wax. Distillation Curve ischaracterized by the initial temperature at which the first drop ofliquid leaves the condenser and subsequent temperatures at each 10 vol %of the liquid. Carbon residue correlates with the amount of carbonaceousdeposits in a combustion chamber. Ash refers to extraneous solids thatreside after combustion. Iodine Value measures the number of doublebonds.

A comparison of properties of biodiesel and EN standard EN590:2005diesel can be found in Table 1.

TABLE 1 EN590 Fuel Property Biodiesel Diesel Density @ 15° C., kg/m³≈885 ≈835 Viscosity @ 40° C., mm²/s ≈4.5 ≈3.5 Cetane Number ≈51 ≈53 90vol % Distillation, ° C. ≈355 ≈350 Cloud Point, ° C. ≈−5 ≈−5 LowerHeating Value, MJ/kg ≈38 ≈43 Lower Heating Value, ≈34 ≈36 MJ/litersPolyaromatics, wt % 0 ≈4 Oxygen, wt % ≈11 0 Sulfur, mg/kg <10 <10

The American Society for Testing and Materials (ASTM) standards forcommercial diesel (ASTM D975) and biodiesel (ASTM D6751) can be found inTable 2.

TABLE 2 Diesel Biodiesel Fuel Property ASTM D975 ASTM D6751 LowerHeating Value, BTU/gal 129,050 118,170 Kinematic Viscosity @ 40° C.,1.3-4.1 4.0-6.0 cSt Specific Gravity @ 60° C., 0.85 0.88 g/cm³ Carbon,wt % 87 77 Hydrogen, wt % 13 12 Oxygen, by dif. wt % 0 11 Sulfur, ppm500 0 Boiling Point, ° C. 180 to 340 315 to 350 Flash Point, ° C. 60 to80 100 to 170 Cloud Point, ° C. −15 to 5    −3 to 12 Pour Point, ° C.−35 to −15 −5 to 10 Cetane Number 40-55 48-65 Lubricity (HFRR), μm300-600 <300

There remains a need for alternative processes for conversion ofvegetable and animal oils to fuels and diesel fuel compositions derivedfrom vegetable and animal oils having better and more acceptableproperties.

SUMMARY

Provided is a process for producing a liquid fuel composition comprisingproviding oil selected from the group consisting of vegetable oil,animal oil, and mixtures thereof and hydrodeoxygenating andhydroisomerizing the oil. The hydrodeoxygenating and hydroisomerizingcomprises feeding the oil to a tubular reaction unit containing acatalyst comprising an acidic component and a metal component, feedingeffluent from the tubular reaction unit to a vapor-liquid separator, andfeeding a vapor phase separated from the effluent from the tubularreaction unit to an adiabatic reaction unit comprising the same catalystas in the tubular reaction unit comprising an acidic component and ametal component. Liquid separated from the effluent from the tubularreaction unit can be recycled to the tubular reaction unit. In anembodiment, the tubular reaction unit is a multi-tubular reaction unitand/or operates in trickle-bed mode and the adiabatic reaction unitcomprises a single tube.

Additionally provided is a reaction system for producing a liquid fuelcomposition comprising a tubular reaction unit containing a catalystcomprising an acidic component and a metal component, an adiabaticreaction unit containing the same catalyst as in the tubular reactionunit comprising an acidic component and a metal component, and avapor-liquid separator disposed between the tubular reaction unit andthe adiabatic reaction unit. The adiabatic reaction unit can be locateddownstream of the tubular reaction unit. In an embodiment, the tubularreaction unit is a multi-tubular reaction unit and/or operates intrickle-bed mode and the adiabatic reaction unit comprises a singletube.

DETAILED DESCRIPTION

High quality liquid fuels, in particular diesel and naphtha fuels, canbe obtained from vegetable and/or animal oils in high yield by a processcomprising hydrodeoxygenation and hydroisomerization. Triglycerides offatty acids contained in the vegetable and/or animal oil aredeoxygenated to form normal C₁₂ to C₁₈ or C₁₄ to C₁₈ paraffins, whichare hydroisomerized in the same stage to form various isoparaffins.Minor cyclization and aromatization to alkyl cyclohexane and alkylbenzene may also occur. The deoxygenation can comprise removal of oxygenin the form of water and carbon oxides from the triglycerides.Hydrocracking is inhibited, so as to maintain the range of carbon numberof hydrocarbons formed in the range of C₁₂ to C₁₈ or C₁₄ to C₁₈.

Hydrodeoxygenation of vegetable and/or animal oils alone would generatea mixture of long-chain straight C₁₂ to C₁₈ or C₁₄ to C₁₈ paraffins.While such long-chain straight C₁₂ to C₁₈ or C₁₄ to C₁₈ paraffins wouldbe in the paraffin carbon number range of diesel fuels, the fuelproperties of such long-chain straight C₁₂ to C₁₈ or C₁₄ to C₁₈paraffins would be significantly different from those of diesel fuels.Therefore, production of diesel fuel requires hydroisomerization of theparaffins. Accordingly, the presently disclosed process for producing aliquid fuel composition comprises providing oil selected from the groupconsisting of vegetable oil, animal oil, and mixtures thereof andhydrodeoxygenating and hydroisomerizing the oil. In addition tohydrocarbon products within the diesel boiling range, the liquid fuelcomposition produced by the presently disclosed process may furthercomprise 2-10% lighter naphtha products boiling below 150° C. as well asheavier distillate products.

The hydrodeoxygenating and hydroisomerizing disclosed herein comprisesfeeding the oil to a tubular reaction unit containing a catalystcomprising an acidic component and a metal component, feeding effluentfrom the tubular reaction unit to a vapor-liquid separator, and feedinga vapor phase separated from the effluent from the tubular reaction unitto an adiabatic reaction unit comprising the same catalyst as in thetubular reaction unit comprising an acidic component and a metalcomponent. While the effluent from the tubular reaction unit isprimarily in a vapor phase, liquid separated from the effluent from thetubular reaction unit can be recycled to the tubular reaction unit. Inan embodiment, the tubular reaction unit, which is contained within ashell, is a multi-tubular reaction unit and/or operates in trickle-bedmode and the adiabatic reaction unit comprises a single tube.

As exothermic hydrodeoxygenation and double-bond saturation reactionstake place in the tubular reaction unit, a significant amount of heat ofreaction is removed from the tube(s) (e.g., 1,000 or even 5,000 tubes)of the tubular reaction unit, for example, by coolant contained in ashell jacketing the tube(s) for optimal temperature control. Thevapor-liquid separator disposed downstream of the tubular reaction unitfunctions as a heat exchanger and sets the temperature of the vaporphase exiting the vapor-liquid separator, which is to be fed to thereaction unit following the vapor-liquid separator. In an embodiment,the vapor phase leaves the vapor-liquid separator at a temperature ofabout 330 to 400° C. As mild, vapor-phase hydroisomerization and similarreactions take place in the reaction unit following vapor-liquidseparation, the reaction unit is adiabatic, and thus, in addition tosetting the temperature of the vapor phase exiting the vapor-liquidseparator, the vapor-liquid separator also sets the temperature of thereaction unit following the vapor-liquid separator and allows foroptimization of the process. Use of both tubular and adiabatic reactionunits allows for optimization of the hydrodeoxygenating andhydroisomerizing and improved performance and stability of the catalyst.The tubular reaction unit, vapor-liquid separator, and adiabaticreaction unit may be contained within one or more reaction vessels.

In an embodiment, catalysts for the presently disclosed process aredual-functional catalysts comprising a metal component and an acidiccomponent. In an embodiment, metal components are platinum or palladium.In an embodiment, the metal component is platinum. The acidic componentcan comprise an acidic function in a porous solid support. In anembodiment, acidic components include, for example, amorphous silicaaluminas, fluorided alumina, ZSM-12, ZSM-21, ZSM-22, ZSM-23, ZSM-35,ZSM-38, ZSM-48, ZSM-57, SSZ-32, ferrierite, SAPO-11, SAPO-31, SAPO-41,MAPO-11, MAPO-31, Y zeolite, L zeolite and Beta zeolite. In anembodiment, the catalyst is Pt/SAPO-11, specifically 0.5-1 wt %Pt/SAPO-11, more specifically 1 wt % Pt/SAPO-11.

The type and content of metal, acid strength, type and concentration ofacid sites, solid porosity and pore size affect the type and quality ofthe diesel fuel produced. U.S. Pat. Nos. 5,082,986, 5,135,638,5,246,566, 5,282,958, and 5,723,716, the entire contents of which arehereby incorporated by reference, disclose representative processconditions using said catalysts for isomerization of differenthydrocarbon feedstock. Further, typical processes and catalysts fordewaxing and hydroisomerization are described, for example, in U.S. Pat.No. 6,702,937, the entire content of which is hereby incorporated byreference, and the references cited therein.

The process is carried out at relatively mild conditions, for example,the tubular reaction unit is operated at conditions comprising a liquidhourly space velocity (LHSV) in the range of 0.5-5 h⁻¹, for example,0.6-3 h⁻¹, 0.7-1.2 h⁻¹, or 1-2.5 h⁻¹, at a temperature varying between300 and 450° C., for example, between 320 and 400° C., at a pressurevarying between 10 and 60 atm, for example, 20-40 atm, and a H₂/oilratio of about 300-1200 NL/L, for example, 500-1000 NL/L. More severeconditions result in liquid fuel compositions with poorer lubricity,while more moderate to mild conditions result in liquid fuelcompositions with better lubricity.

Lubricity is especially important with regard to modern diesel fuels, asmodern engines have very high injection pressures in excess of 24,000pounds per square inch. Good lubricity is necessary to prevent risk ofcatastrophic engine failure. In general, an acceptable lubricity refersto a lubricity that would allow modern engines to operate moreefficiently. In an embodiment, the diesel fuel has a maximumhigh-frequency reciprocating rig (HRFF) lubricity of 400 μm (accordingto International Organization for Standardization (ISO) standard12156/1), in accordance with the recommendation of the World Wide FuelCharter, Category 4. In an embodiment, the lubricity is less than 300 μmaccording to ISO 12156/1, for example, the lubricity is less than 200 μmaccording to ISO 12156/1.

Any vegetable and/or animal oil can be used in the presently disclosedprocess. For example, suitable vegetable oils include soybean oil, palmoil, corn oil, sunflower oil, oils from desertic plants such as, forexample, jatropha oil and balanites oil, rapeseed oil, colza oil, canolaoil, tall oil, safflower oil, hempseed oil, olive oil, linseed oil,mustard oil, peanut oil, castor oil, coconut oil, and mixtures thereof.In an embodiment, vegetable oils include soybean oil, palm oil, cornoil, sunflower oil, jatropha oil, balanites oil, for example, fromBalanites aegyptiaca, and mixtures thereof. The vegetable oil may begenetically modified oil, produced from transgenic crops. The vegetableoil may be crude vegetable oil or refined or edible vegetable oil. Ifcrude vegetable oil is used, the vegetable oil can be pretreated, forexample, to separate or extract impurities from the crude vegetable oil.Suitable animal oils include, for example, lard oil, tallow oil, trainoil, fish oil, and mixtures thereof. Further, the vegetable and/oranimal oil may be new oil, used oil, waste oil, or mixtures thereof.

The oil, or mixture of oils, used in the presently disclosed process cancontain a high content of fatty acids (e.g., greater than or equal to 70wt % fatty acids). Additionally, compositions derived from vegetableand/or animal oil that contains a high content of fatty acids can beused in the presently disclosed process. The phrase “compositionsderived from vegetable and/or animal oil” refers to compositions whichoriginate from or are the byproduct of processing vegetable and/oranimal oil (e.g., vapor overhead stream from distilling vegetable and/oranimal oil, residual non-vaporizable remaining portion, etc.). Thus,palm oil distillate containing greater than 70 wt % fatty acids can beused in the presently disclosed process.

The diesel fuel composition produced by the presently disclosed methodscomprises a mixture of C₁₂ to C₁₈ or C₁₄ to C₁₈ paraffins with a ratioof iso to normal paraffins from 0.5 to 8, for example, from 2 to 8, from2 to 6, from 2 to 4, from 1 to 4, or from 4 to 7; less than 5 ppmsulfur, for example, less than 1 ppm sulfur; and acceptable lubricity.Specifically, the diesel fuel composition can have a lubricity of lessthan 400 μm, for example, less than 300 μm or less than 200 μm,according to ISO 12156/1.

Additionally, the diesel fuel composition can comprise less than orequal to 0.6 wt %, for example, 0.1-0.6 wt %, of one or more oxygenatedcompounds, which, without wishing to be bound by any theory, arebelieved to contribute to the acceptable lubricity of the diesel fuelcomposition. In an embodiment, the one or more oxygenated compoundscomprise acid, for example, one or more fatty acids. In an embodiment,the one or more oxygenated compounds (e.g., acid), is present in anamount of less than or equal to 0.4 wt %, for example, 0.1-0.4 wt %. Asused herein, the phrase “fatty acids” refers to long chain saturatedand/or unsaturated organic acids having at least 8 carbon atoms, forexample, 12 to 18 or 14 to 18 carbon atoms. Without wishing to be boundby any theory, it is believed that the low content of one or moreoxygenated compounds, for example, one or more fatty acids, in thediesel fuel composition may contribute to the acceptable lubricity of adiesel fuel composition; such oxygenated compounds, present in thevegetable and/or animal oil feedstock, may survive the non-severehydrodeoxygenation/hydroisomerization conditions employed in thepresently disclosed process. The diesel fuel composition may comprisealkyl cyclohexane, for example, less than 10 wt %, and/or alkyl benzene,for example, less than 15 wt %.

The characteristics of the diesel fuel composition, and naphtha,produced by the presently disclosed methods may vary depending on thevegetable and/or animal oil starting product, process conditions, andcatalyst used. In an embodiment, selection of vegetable and/or animaloil starting product, process conditions, and catalyst allows for highyield of high quality diesel fuel composition, with preferredproperties, and minimized production of lighter components including,for example, naphtha, carbon oxides and C₁ to C₄ hydrocarbons. Theparaffinic diesel fuel compositions produced by the presently disclosedmethods provide superior fuel properties, especially for low temperatureperformance (e.g., density, viscosity, cetane number, lower heatingvalue, cloud point, and CFPP), to biodiesel, a mixture of methyl orethyl esters. In contrast to the products of the process disclosed inU.S. Patent Publication No. 2004/0230085, disclosed herein are methodfor producing diesel fuel compositions with acceptable lubricitiesproduced from vegetable and/or animal oil. More specifically, fuelproperties, such as, for example, lubricity, may be controlled throughvariation of process conditions and/or catalyst(s). In general, withregards to the distillation curve of the diesel fuel compositionproduced by the presently disclosed methods, the initial boiling point(IBP) is in the range of 160° C.-240° C. and the 90 vol % distillationtemperature is in the range of 300° C.-360° C. The produced naphtha ishighly pure and particularly suitable for use as a solvent and/orchemical feedstock, e.g., a cracking stock.

EXAMPLES

The following examples are intended to be non-limiting and merelyillustrative.

Comparative Example 1 Production of Diesel from Soybean Oil Based onU.S. Patent Publication No. 2004/0230085

Refined soybean oil was fed to a fixed-bed reactor packed with agranulated Ni—Mo catalyst operated at an LHSV of 1.0 h⁻¹, 375° C., 40atm, and an H₂/oil ratio of 1200 NL/L (Stage 1). The total liquidproduct was separated into two phases, water and an organic phase. Theorganic phase was fed to a fixed-bed reactor packed with a granulated 1wt % Pt/SAPO-11 catalyst operated at an LHSV of 3.0 h⁻¹, 380° C., 50atm, and an H₂/oil ratio of 500 NL/L (Stage 2). The organic phase fromStage 1 and the diesel product from Stage 2 were analyzed according toASTM methods and their compositions were measured by GC-MS and confirmedby NMR. The results can be found in Table 3.

TABLE 3 Comparative Comparative Example 1 Example 1 Stage 1 Stage 2 OilSoybean Soybean Temperature 375° C. 380° C. Catalyst GranulatedGranulated Ni—Mo 1 wt % Pt/ SAPO-11 LHSV, hr⁻¹ 1.0 3.0 Pressure, atm 4050 H₂/oil ratio, NL/L 1200 500 Distillation Temperature ASTM D86 IBP194.1° C. 150° C. 10% 292.8° C. 191.1° C. 50% 303.6° C. 295.4° C. 90%369.0° C. 356.0° C. Up to 250° C. 2.0% 18.1% Up to 350° C. 86.5% 89.4%Cold Filter Plugging Point (CFPP) 17° C. <−20° C. IP 309 Lubricity(HFRR) 352 μm 502 μm ISO 12156/1 Cloud Point 17° C. <−20° C. ASTM D2500Kinematic Viscosity @ 40° C. 5.25 cSt 2.97 cSt ASTM D445 SpecificGravity @ 15° C. 0.806 g/cm³ 0.788 g/cm³ ASTM D1298 Composition, wt %Linear paraffins 51.0 14.0 Branched paraffins 28.0 76.8 Alkylcyclohexane 9.2 5.5 Alkyl benzene 2.2 0.6 Olefins 2.7 0.3 Acids 0.2 NotDetected* Others 6.7 2.8 Degree of saturation 0.6 0.8 ASTM D1959-97*Detection limit of 0.1 wt %

The diesel product from Stage 2 exhibited a poorer lubricity (502 μm) ascompared to that of the organic phase from Stage 1 (352 μm). Withoutwishing to be bound by any theory, it is believed that the increase inratio of branched to linear paraffins in the diesel product from Stage2, as compared to the organic phase from Stage 1, resulted in a changeof fuel properties.

Comparative Example 2 Production of Diesel from Soybean Oil by a TwoStage Process

Refined soybean oil was fed to a fixed-bed reactor packed with agranulated 1 wt % Pt/SAPO-11 catalyst operated at an LHSV of 1.0 h⁻¹,380° C., 20 atm, and an H₂/oil ratio of 1200 NL/L (Stage 1). The totalliquid product was separated into two phases, water and diesel product.The diesel product from Stage 1 was fed to a fixed-bed reactor packedwith a granulated 1 wt % Pt/SAPO-11 catalyst operated at an LHSV of 4.5h⁻¹, 360° C., 30 atm, and an H₂/oil ratio of 1200 NL/L (Stage 2). Thediesel product from Stage 1 and the diesel product from Stage 2 wereanalyzed according to ASTM methods and their compositions were measuredby GC-MS and confirmed by NMR. The results can be found in Table 4.

TABLE 4 Comparative Comparative Example 2 Example 2 Stage 1 Stage 2 OilSoybean Soybean Temperature 380° C. 360° C. Catalyst GranulatedGranulated 1 wt % Pt/ 1 wt % Pt/ SAPO-11 SAPO-11 LHSV, hr⁻¹ 1.0 4.5Pressure, atm 20 30 H₂/oil ratio, NL/L 1200 1200 DistillationTemperature ASTM D86 IBP 181.3° C. 189.7° C. 10% 263.9° C. 263.5° C. 50%292.5° C. 292.6° C. 90% 360.3° C. 353.7° C. Up to 250° C. 5.6% 5.4% Upto 350° C. 88.9% 89.7% Cold Filter Plugging Point (CFPP) −14° C. −17° C.IP 309 Lubricity (HFRR) 306 μm 437 μm ISO 12156/1 Cloud Point −12° C.−14° C. ASTM D2500 Kinematic Viscosity @ 40° C. 3.82 cSt 3.60 cSt ASTMD445 Specific Gravity @ 15° C. 0.789 g/cm³ 0.794 g/cm³ ASTM D1298Composition, wt % Linear paraffins 26.8 23.6 Branched paraffins 52.358.4 Alkyl cyclohexane 4.9 8.1 Alkyl benzene 7.7 2.9 Olefins 2.9 2.9Acids 0.4 Not Detected* Others 5.0 4.1 Degree of saturation 0.4 0.5 ASTMD1959-97 *Detection limit of 0.1 wt %

The diesel product from Stage 1 exhibited acceptable properties,including a lubricity of 306 μm. As the composition of the dieselproduct from Stage 2 did not significantly differ from the dieselproduct from Stage 1, the properties of the diesel product from Stage 2are similar to those of the diesel product from Stage 1. However, thediesel product from Stage 2 exhibited a poorer lubricity (437 μm) ascompared to that of the diesel product from Stage 1 (306 μm), similar tothe diesel production from Stage 2 of Comparative Example 1. Withoutwishing to be bound by any theory, it is believed that water may act asan inhibitor to isomerization, which requires higher catalyst activity,and the removal of water between Stage 1 and Stage 2 in ComparativeExample 1 and Comparative Example 2 may also remove acid, therebyaffecting final product lubricity.

Adding 0.1 wt % of oleic acid to the diesel product of Stage 2 improvedits lubricity from 437 μm to 270 μm. Thus, as noted above, withoutwishing to be bound by any theory, it is believed that the low contentof one or more oxygenated compounds, such as one or more fatty acids, inthe product of the process may contribute to the acceptable lubricity ofthe diesel product.

Example 3 Production of Diesel from Soybean Oil in a Two Unit Process

The reactor setup and the operating conditions of Example 3 were basedon the results of kinetic studies and reactor simulations using soybeanoil. In the kinetic studies, concentrations of the soybean oil, acids,paraffins, olefins, cyclohexanes, aromatics and light compounds weremeasured as a function of residence time and temperature. Vapor-liquidequilibrium was provided by the reactor simulations. For a residencetime of 15 to 25 minutes, the soybean oil was nearly completelyconverted. The acid content in the product(s) peaked at about 10 to 15minutes, and then decreased with additional residence time. Again,diesel fuel compositions produced in accordance with the presentlyclaimed methods can comprise less than or equal to 0.6 wt % of one ormore oxygenated compounds (e.g., acids). In part due to the operatingpressure, conversion of the soybean oil (e.g., for a residence time of15 to 25 minutes) resulted in vapor phase products with only very smallamounts of liquid products, which contain heavy compounds (e.g., C₂₀₊hydrocarbons).

Accordingly, refined soybean oil was fed to a single (electricallyheated) wall-cooled reactor tube, packed with a granulated 1 wt %Pt/SAPO-11 catalyst, and operated in trickle-bed mode at an LHSV of 3.5h⁻¹, 382° C., 30 atm, and an H₂/oil ratio of 550 NL/L. The effluent ofthe single wall-cooled reactor tube flowed through a gas-liquidseparator maintained at 30 atm and 373° C., in which a very small amountof liquid (i.e., 0.2 wt % of the refined soybean oil fed to the singlewall-cooled reactor tube) was separated from a vapor phase. The vaporphase from the separator flowed upward to a single tube, adiabatic,fixed-bed reaction unit packed with a granulated 1 wt % Pt/SAPO-11catalyst operated at an LHSV of 1.4 h⁻¹, 373-375° C., 30 atm, and anH₂/oil ratio of 550 NL/L. The diesel product from the adiabatic reactionunit was analyzed according to ASTM methods and its composition wasmeasured by GC-MS. The results can be found in Table 5.

TABLE 5 Example 3 Distillation Temperature ASTM D86 IBP 143.8° C. 10%268.5° C. 50% 293.6° C. 90% 355° C. Up to 250° C. 5.1% Up to 350° C.89.7% Cold Filter Plugging Point (CFPP) −20° C. IP 309 Lubricity (HFRR)346 μm ISO 12156/1 Flash Point 59° C. Kinematic Viscosity @ 40° C. 3.76cSt ASTM D445 Specific Gravity @ 15° C. 0.802 g/cm³ ASTM D1298Composition, wt % Linear paraffins 20 Branched paraffins 64 Alkylcyclohexane 7 Alkyl benzene 7 Olefins 2 Acids 0.2

The diesel product according to Example 3 exhibited acceptableproperties, including a lubricity of 346 μm.

The temperature of the adiabatic reaction unit following thevapor-liquid separator is set by the temperature of the vapor-liquidseparator. Heat loss can cause a temperature drop in the vapor phaseproducts from the tubular reaction unit. Assuming that heat loss isavoided, if the temperature of the vapor-liquid separator is low (i.e.,lower than the temperature of the vapor phase products from the tubularreaction unit), the vapor phase products may undesirably condense toliquid prior to hydroisomerization in the adiabatic reaction unit.Therefore, the temperature of the vapor-liquid separator can be set suchthat the temperature of the vapor-liquid separator is close to thetemperature of the tubular reaction unit, and more specifically, thetemperature of the vapor phase products from the tubular reaction unit.Most of the heat of the hydrodeoxygenation and hydroisomerizationreaction is generated in the tubular reaction unit, which can be awall-cooled reactor. Accordingly, the reaction unit downstream of thevapor-liquid separator can be run adiabatically. The vapor-liquidseparator, which can provide different conditions in the downstreamadiabatic reaction unit than in the upstream tubular reaction unit, canalso ensure that the downstream adiabatic reaction unit is run in vaporphase.

For example, the temperature of the adiabatic reaction unit followingthe vapor-liquid separator can be set in the range of about 350 to 400°C. or about 360 to 385° C. In particular, the temperature of thevapor-liquid separator in Example 3 was maintained at 373° C. and thetemperature of the adiabatic reaction in Example 3 was operated at 373°C., to minimize condensation of vapor phase products to liquid prior tohydroisomerization in the adiabatic reaction unit. Thus, thevapor-liquid separator can be used to set the temperature of theadiabatic reaction unit following the vapor-liquid separator.

As noted above, the effluent from the single wall-cooled reactor tube isprimarily in a vapor phase (e.g., vapor phase can comprise about 95 to99.9 wt % of the effluent). The liquid separated from the vapor phase inthe vapor-liquid separator can contain as much as 40 wt % acids. Thecatalyst contained in the reaction units is sensitive to coking anddeactivation as a result of contact with heavy compounds (e.g., acids)in the liquid products. Thus, liquid products can negative affectselectivity of desired products and stability of the catalyst.Accordingly, separation of liquid from the vapor phase in thevapor-liquid separator (i.e., the vapor phase to be fed to the adiabaticreaction unit), protects catalyst in the adiabatic reaction unit andprevents deactivation thereof. Consequently, while catalyst in theupstream tubular reaction unit can be prone to deactivation as a resultof contact with heavy compounds (e.g., acids) in the liquid products,separating liquid product in the vapor-liquid separator prior to thedownstream adiabatic reaction unit can avoid the need to regeneratecatalyst in the downstream adiabatic reaction unit. Thus, use of bothtubular (e.g., single wall-cooled reactor tube or multi-tubular) andadiabatic reaction units, and a vapor-liquid separator disposedtherebetween, allows for improved performance and stability of thecatalyst, especially the catalyst contained within the adiabaticreaction unit. In particular, the life of the catalyst contained withinthe adiabatic reaction unit can be extended as a result of using avapor-liquid separator disposed between the tubular and adiabaticreaction units.

While various embodiments have been described, it is to be understoodthat variations and modifications can be resorted to as will be apparentto those skilled in the art. Such variations and modifications are to beconsidered within the purview and scope of the claims appended hereto.

1. A process for producing a liquid fuel composition comprising:providing oil selected from the group consisting of vegetable oil,animal oil, and mixtures thereof; and hydrodeoxygenating andhydroisomerizing the oil, wherein the hydrodeoxygenating andhydroisomerizing comprises: feeding the oil to a tubular reaction unitcontaining a catalyst comprising an acidic component and a metalcomponent; feeding effluent from the tubular reaction unit to avapor-liquid separator; and feeding a vapor phase separated from theeffluent from the tubular reaction unit to an adiabatic reaction unitcomprising the same catalyst as in the tubular reaction unit comprisingan acidic component and a metal component.
 2. The process of claim 1,wherein the tubular reaction unit comprises a multi-tubular reactionunit.
 3. The process of claim 1, wherein hydrodeoxygenating occurs inthe tubular reaction unit and hydroisomerizing occurs in the adiabaticreaction unit.
 4. The process of claim 1, further comprising recyclingliquid separated from the effluent from the tubular reaction unit to thetubular reaction unit.
 5. The process of claim 1, wherein the tubularreaction unit operates in trickle-bed mode.
 6. The process of claim 1,wherein the adiabatic reaction unit comprises a single tube.
 7. Theprocess of claim 1, comprising operating the tubular reaction unit atconditions comprising: a liquid hourly space velocity of 0.5 to 5 hr⁻¹;a temperature of 300 to 450° C.; a pressure of 10 to 60 atm; and aH₂/oil ratio of 300 to 1200 NL/L.
 8. The process of claim 1, wherein thevapor phase has a temperature of about 330 to 400° C.
 9. The process ofclaim 1, comprising operating the adiabatic reaction unit at atemperature of about 350 to 400° C.
 10. The process of claim 1, whereinthe metal component is selected from the group consisting of platinumand palladium and the acidic component is selected from the groupconsisting of amorphous silica alumina, fluorided alumina, ZSM-12,ZSM-21, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-57, SSZ-32,ferrierite, SAPO-11, SAPO-31, SAPO-41, MAPO-11, MAPO-31, Y zeolite, Lzeolite, and beta zeolite.
 11. The process of claim 9, wherein thecatalyst is Pt/SAPO-11.
 12. The process of claim 10, wherein thecatalyst is 0.5-1 wt % Pt/SAPO-11.
 13. The process of claim 1, whereinthe vegetable oil is selected from the group consisting of soybean oil,palm oil, corn oil, sunflower oil, jatropha oil, balanites oil, rapeseedoil, colza oil, canola oil, tall oil, safflower oil, hempseed oil, oliveoil, linseed oil, mustard oil, peanut oil, castor oil, coconut oil, andmixtures thereof.
 14. The process of claim 1, wherein the animal oil isselected from the group consisting of lard oil, tallow oil, train oil,fish oil, and mixtures thereof.
 15. A reaction system for producing aliquid fuel composition comprising: a tubular reaction unit containing acatalyst comprising an acidic component and a metal component; anadiabatic reaction unit comprising the same catalyst as in the tubularreaction unit comprising an acidic component and a metal component; anda vapor-liquid separator disposed between the tubular reaction unit andthe adiabatic reaction unit.
 16. The reaction system of claim 15,wherein the tubular reaction unit comprises a multi-tubular reactionunit.
 17. The reaction system of claim 15, wherein the adiabaticreaction unit comprises a single tube.
 18. The reaction system of claim15, wherein the tubular reaction unit operates in trickle-bed mode. 19.The reaction system of claim 15, wherein the adiabatic reaction unit islocated downstream of the tubular reaction unit.
 20. The reaction systemof claim 15, wherein the metal component is selected from the groupconsisting of platinum and palladium and the acidic component isselected from the group consisting of amorphous silica alumina,fluorided alumina, ZSM-12, ZSM-21, ZSM-22, ZSM-23, ZSM-35, ZSM-38,ZSM-48, ZSM-57, SSZ-32, ferrierite, SAPO-11, SAPO-31, SAPO-41, MAPO-11,MAPO-31, Y zeolite, L zeolite, and beta zeolite.